The application of hollow micro-/nanostructured cathodes for sodium-ion batteries

High-performance sodium-ion batteries （SIBs） rely on efficient cathodes, constructed based on advances in excellent rate capability, high capacity, and small volume change. Cathode materials with micro-/nano-hollow architectures can shorten the diffusion length, offer volume buffering, and increase the conducting capability of electrons/ions, so that they have received extensive development as a new strategy for the exploration of future cathodes. This review offers a snapshot of the recent progress on the synthetic strategies used to prepare hollow cathodes, their improved battery performance, and the mechanism of sodium storage underlying the use of hollow micro-/nanostructured cathode materials. Finally, we provide an overview of likely future directions in this research, which includes seeking the right balance between volumetric capacity and energy density.